In the past, for a device that monitors an assembled battery comprising a plurality of cells, a cell balancing technique has been per se known in which variation of the remaining charge capacities of the various cells has been eliminated by calculating the remaining charge capacity of each cell, and by controlling balancing switches that are provided to correspond to the various cells on the basis of the results of that calculation. A technique for reducing the consumption of electrical power during this type of cell balancing is disclosed in PTL 1.
With the battery control system disclosed in PTL 1, along with providing a CMOS timer IC to correspond to each cell in the interior of a battery control unit that is connected to the assembled battery, also a timer is provided within a system control unit that is employed for performing communication with the battery control unit. By using these timers, it is arranged to operate only the minimum limit number of capacity adjustment circuits within the battery control unit that are actually required during cell balancing, so that thereby the consumption of electrical power is reduced.